Questions tagged [rocket-science]
Colloquially referred to as one of the hardest professions, rocket science is actually a common name for spacecraft/space-systems engineering. However, one can also generalize this to include all forms of rocketry, including rockets that are not capable of space travel.
807 questions
1 vote
0 answers
162 views
What is the difference in the definition of blunt body at supersonic vs subsonic speeds?
This question is related to space exploration and the shape of the body entering the atmosphere. I did get an opinion that at supersonic speeds, an elongated cylinder (SpaceX Starship second stage) ...
1 vote
2 answers
165 views
How to free fall on a planet?
Suppose you are orbiting a planet at a tangential speed of $u$. If we accelerated in the opposite direction of the tangential speed with a acceleration $a$ for $t$ seconds such as $at=-u$ wouldn't ...
- 265
4 votes
5 answers
1k views
Aircraft propelled by Liquid Rocket Engines
I heard of aircraft whose thrust is assisted by solid propellant rockets when the main engine uses conventional Jet aviation fuel. I also heard of bi-propellants in liquid rocket applications which ...
- 1,305
-1 votes
1 answer
194 views
How do I calculate the speed of a falling object given time and nothing else? [closed]
How do I calculate the speed of an object given the gravitational pull and the time the object is falling? All the calculators I find want to know the height the object has fallen from. I found the ...
- 117
1 vote
0 answers
272 views
What is the best way for optimisation? (Rocket from Earth to Mars)
I would like to consider a rocket impulse plan from Earth to Mars for my Personal Project (IB-MYP) I am currently working on, and I am a student in high school in Hiroshima, Japan. Could you please ...
- 37
7 votes
2 answers
727 views
Is there an upper limit to acceleration?
Dr. Blitz, a physicist and YouTuber stated that due to kinematic equations on how a spaceship would contract if it was going very fast shows us that the back of the ship cannot accelerate infinitely. ...
- 217
11 votes
3 answers
2k views
Advantage of launching a rocket from the Equator
I have recently read the following in a book: As a result of the Earth’s rotation, objects on its surface would be flung off were it not for the Earth’s gravity holding them down. In fact, this “...
- 327
0 votes
1 answer
85 views
Ultrasonic Magnetic Distortion Preventing Liftoff? [closed]
If someone was broadcasting an ultrasonic magnetic distortion over a wide enough area, could it prevent the ignition of rocket engines, hence preventing liftoff? What exactly is an ultrasonic ...
- 129
2 votes
1 answer
203 views
Derivation of rocket propulsion equation - clarification
On a rocket accelerating upward, the forces acting are i) the rocket's weight downward ii) thrust force upward, due to ejection of gas We may write $ -u_e dm/dt-mg= F_{ext} $ where $dm/dt$ is the ...
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-1 votes
1 answer
149 views
How slow can you alternate a set of thrusters to reach an equivalent total thrust? [closed]
Say I have a pair of magic thrusters. Each can output roughly 1N of force. They are attached to a 1kg body. When both of them are on at the same time (delay interval Φ=0s), the body would experience ...
- 19
4 votes
3 answers
497 views
Rocket Motion treatment by Kleppner and Kolenkow
I was going through the "Rocket Motion" section of An Introduction to Mechanics by Kleppner and Kolenkow, where something caught my attention. To begin with, I am going to put a part of ...
- 2,021
4 votes
2 answers
267 views
Where does the energy from your muscles go when you lift a rock in a rocket?
My friends and I have been struggling with a seemingly simple physics problem. The question is about what happens to the energy in various different situations when you lift a rock onto a shelf and ...
- 43
3 votes
1 answer
338 views
Deriving the Rocket Equation from Hamilton's Principle
I've been trying to derive the rocket equation ($ m \ddot{x} = - \dot{m} v_e $) from Hamilton's Principle and I've hit a wall. The way I went about it was by extremizing the action $ S = \int L dt $, ...
- 31
1 vote
1 answer
128 views
Achieving supersonic speeds in a purely diverging nozzle
To achieve supersonic flow $M>1$ we have to have a converging-diverging nozzle (like de Laval nozzle). Is it still possible to achieve supersonic flow $M>1$ only with a diverging nozzle, ...
- 1,586
7 votes
4 answers
1k views
Bicycle Oberth effect
I know of the Oberth effect, which states that it is more efficient to put in work at high velocity. It is usually applied to orbital mechanics, but the explanations I saw only talk about kinetic and ...
